The general objective of the study was to establish the effect of risk management processes on performance of borehole projects in Mombasa County, Kenya. Descriptive research design was used. The study focused on 146 borehole projects in Mombasa County, Kenya, undertaken from 2013 to 2018 and focusing on two key units of respondents per each project comprising of project manager and one end user representative per project. The study population was 182 respondents (project managers, clients and contractors). Stratified random sampling techniques was adopted. Structured questionnaires were used to collect primary data from the targeted respondents. Quantitative data was analyzed by use of both inferential and descriptive statistics with the help of statistical software known as Statistical Package for Social Sciences (SPSS version 25). The study found out that there was a positive and significant relationship between project risk identification and performance of borehole projects in Mombasa County, Kenya. There was a positive and significant relationship between project risk evaluation and performance of borehole water supply construction projects in Mombasa County, Kenya. Also There was a positive and significant relationship between project risk handling and performance of borehole projects in Mombasa County, Kenya. Lastly, there was a positive and significant relationship between project risk control and performance of borehole projects in Mombasa County, Kenya. Based on the findings, the study concluded that risk identification, risk evaluation, risk handling and risk control have a positive and significant effect on the performance of borehole projects in Mombasa County, Kenya. The study recommended that project managers should embrace the use of risk identification because it assists the management to develop risk management strategy to allocate resources efficiently, organizations should adopt project's accounting control practices such as risk based auditing, projects should transfer risks through diversification and hedging and lastly, many project policies, although popular should be avoided, but avoiding risks also means losing out on the potential gain that accepting (retaining) the risk may have allowed.